Effects of graphene oxide on grape growth, rhizosphere microbial diversity, and berry quality.

Grape (Vitis vinifera L.) is an economically important fruit crop worldwide, with berry size and quality determining yield and market value. Graphene oxide (GO), a carbon nanomaterial with high specific surface area and abundant oxygen-containing functional groups, exhibits excellent fertilizer adsorption, holding promise for agricultural applications. This study systematically evaluated the effects of exogenous GO application on growth, rhizosphere microecology, and berry quality in 'Crimson Seedless' grape. The results showed that, compared with the control, treatment with 25 mg/L GO significantly promoted the plant height, stem diameter, and biomass accumulation of grape seedlings, and enhanced photosynthetic capacity. Rhizosphere soil microbial diversity analysis revealed that GO treatment increased the abundance and diversity of both bacteria and fungi. Further species composition and Linear discriminant analysis Effect Size (LEfSe) analysis indicated that GO treatment significantly enriched potentially beneficial microorganisms in the grape rhizosphere, including Bacillus, Sphingomonas, RB41, and Mortierella. Soil physicochemical property measurements demonstrated that, compared with the control, GO significantly increased the contents of soil organic matter, total nitrogen, ammonium nitrogen, available potassium, and humic acid by 26.29%, 65.57%, 26.02%, 181.79%, and 14.05%, respectively, while reducing total phosphorus, total potassium, and available phosphorus. Regarding fruit quality, GO significantly increased berry weight, firmness, shape index, and contents of total sugar, vitamin C, soluble solids, tannins, anthocyanins, calcium and 23 Amino acid in berries compared with both the control and Bayer fertilizers (BR, Bayer AG, Cat: Dabs-1L) treatment. Collectively, these findings elucidate GO-mediated growth promotion and fruit quality regulation in grape, providing a theoretical and practical basis for broader agricultural GO application.